Isolators are typically automatic solid state devices which allow a user to connect an engine alternator directly to two or more batteries simultaneously. Isolators avoid overcharging or discharging by a higher charged battery into a lower charged battery.
For example, battery isolators are typically disposed between the alternator of an engine and multiple batteries in such a manner as to permit electrical current to flow only in one direction, i.e., from the alternator to the batteries via the isolator. During the operation of the engine, each battery is electrically isolated from the other and charged independently.
One conventional electrical isolator includes a finned anodized aluminium extrusion with a central holding area. FIGS. 10 and 11 depict such an electrical isolator 1 which includes an aluminium extrusion 2, central holding area 3, metal stud 4 and diodes 5. Central holding area 3 contains a metal plate (heat sink) 6 in which metal stud 4 and diodes 5 are either press fit and/or screwed therein.
A thermally conductive layer 7 is disposed about the walls of central holding area 3 in order to electrically isolate aluminium extrusion 2 from metal plate 6, while permitting heat conductivity therebetween. That is, heat from metal plate 6 is conducted from central holding area 3 via thermally conductive layer 7 to aluminium extrusion 2 which acts as a cooling system, i.e., heat is dissipated from the isolator assembly via the finned members of aluminium extrusion 2.
Aluminium end caps 8 and 9 are disposed at opposite ends of central holding area 3. Once aluminium end caps 8 and 9 are in place an epoxy filler 10 is poured into central holding area 3 for the purpose of isolating stud 4, diodes 5, metal plate 6 and thermally conductive layer 7 from outside contact. Epoxy filler 10 is cured in an oven for several hours.
The aforementioned conventional aluminium extrusion electrical isolator is extremely expensive and tedious to manufacture. The present inventor has developed a novel electrical isolator device which is much simpler to manufacture, designed as a self-contained unit, and produced at a substantial savings verses the aluminium extrusion devices.
The present invention does not require the use of costly finned aluminium extrusions as a cooling mechanism. It also overcomes the dangers of exposed aluminium extrusions which can be hazardous to operators if touched during normal operations. The present invention also overcomes the need for the time consuming step of pouring epoxy filler into the central holding area and curing for several hours. Use of an expensive thermally conductive layer is also avoided by the design of the present invention.
The self-contained electrical isolator device of the present invention performs all the same functions of conventional aluminium extrusion devices, i.e., electrical isolation and heat dissipation, but at a substantial savings in both manufacturing cost and time. Furthermore, the present invention is designed such that its heat sink (steel plate) is exposed to the air to allow the dissipation of heat, electrically isolated by a non-conductive housing, and not exposed to operators. This avoids the need for the use of an expensive aluminium extrusion cooling system which is directly exposed to the operator. The non-conductive housing of the present invention also eliminates the need for costly aluminium end caps, epoxy filler (which is both costly and time consuming) and a thermally conductive layer.
Therefore, the present invention provides an electrical isolator which is much simpler to manufacture, includes substantially less parts, less expensive, shorter manufacturing process, easier to handle, light weight, and less hazardous to operators.
The present invention also provides many additional advantages which shall become apparent as described below.